Electrical cables, chiefly when used in vehicles and electrical machines, are made to be highly flexible, with multi-wire conductor construction in the form of at least one litz wire having litz wire strands. The electrical insulation of the litz wire is usually carried out in an extrusion operation, through which the litz wire becomes completely surrounded with insulation material in the form of an insulation sheath. In order to obtain a flexible, bendable cable, it is necessary that the litz wire strands be disposed as close as possible to each other and that a lengthwise balancing of the litz wire strands when the conductor is bent be enabled by twisting them.
The laying of the litz wire strands close together produces voids, which are disposed in narrow channels between the litz wire strands along the cable. These thin channels produce a capillary pressure, which is capable of drawing water into the cable. Temperature variations between the ends of the cable, which may occur in use, can cause varying pressure differences in the cable, through which the water can be transported through the cable, until it has ultimately migrated through the entire cable. This can lead to corrosion of contact points.
To solve this problem, in the prior art both cable ends are elaborately sealed. In the case of plug connections this problem is solved through the construction of sealed plug housings. If one-sided cable eyes are used, a shrinkable boot with internal adhesive is usually employed.
However, since the threaded surface of the cable eye is unprotected, a seal cannot be achieved over its lifetime because of corrosion. As soon as water penetrates into the cable, the opposing contact points are thus also threatened.
To prevent a lengthwise transport of water, it is also known from the prior art that a separation of the conductor takes place, in particular between the wet region and dry region, and a sealed transition support point or connector is used, which is either screwed or crimped to the at least one litz wire. This solution is costly and increases the overall electrical resistance, which can be problematic in particular in the case of the onboard electrical networks of vehicles. An example of such a solution is disclosed in DE 202009013471 U1.
It is known from each of DE 102011083952 A1, U.S. Pat. No. 5,846,467 A, and DE 3903059 A1, for sealing or interruption of a capillary flow transport, to birdcage a bundle of litz wires or a litz wire and to fill the resulting space between the litz wires or the litz wire strands with sealing material.